Which pair contains only physical quantities that vary with temperature and so could be used in making a thermometer?

A activity of a radioactive source, volume of a gas
B mass of a liquid, volume of a liquid
C activity of a radioactive source, mass of a solid
D volume of a gas, volume of a liquid

we need to know the time interval during which the force acts. impulse of force = momentum change

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.